Egg cartons are subjected to multiple adverse mechanical forces and environmental conditions during filling, handling and transport between distribution centers, store shelves, and the ultimate consumer's home. They typically encounter automated equipment for filling, packaging, loading, unloading, stacking, restacking and transport. During each of these encounters, the goal is to resist egg breakage by stabilizing and holding the eggs in a protected environment, in a carton that can be manufactured in a cost effective manner.
Thus, many factors are taken into consideration in the design of egg cartons. Egg protection, resistance to stress or force, stackability, transportability, moisture resistance, aesthetic appearance, print surface area, weight, nestability/denestability, adaptability to accommodate various size eggs, and consistent manufacturing are factors which may be considered to varying degrees in the design of an egg carton.
Plastic egg cartons are available with flexible walls between the cell pockets to protect the eggs and prevent them from moving into adjacent cell pockets. However, during handling, such as while loading cases of egg cartons onto a grocery pallet, and then stacking the cases 5 to 6 high on the pallet, the cases/cartons may be thrown onto the pallets and/or bump into each other, causing the eggs to come out of their cell pockets and make contact from a hard side impact blow. Also, when scanning bar codes on lid tops, the eggs can be displaced and make contact. While one carton design may provide structural re-enforcements that accommodate and protect a specific egg size (e.g., medium, large, extra-large, or jumbo), few cartons can accommodate a range of sizes or even the variation in size that often occurs within a specific egg size category. For example, jumbo eggs can vary between super jumbo (weighing from 34 to 36 ounces per dozen, or 2.83 to 3.00 ounces per egg) and regular jumbo (weighing from 30 to 33 ounces per dozen or 2.5 to 2.75 ounces per egg). If even one egg out of a dozen moves in its cell pocket because it is slightly wider or shorter than the typical egg in the size group for which the carton was designed, it creates broken eggs for the retailer to clean up and one or more un-saleable cartons depending upon how far the broken egg results travel.
Thus, there is need for an improved egg carton construction to provide better egg protection for eggs of varying dimensions while encountering the adverse mechanical forces and environmental changes that typically occur during filing, packaging, transportation and storage. At the same time, there is a need to manufacture such cartons in a cost effective manner, provide overall carton dimensions that fit within standard case sizes and avoid a redesign of the existing handling equipment.